On Mon, Aug 20, 2012 at 09:10:59PM +0100, Arnd Bergmann wrote: > On Monday 20 August 2012, Will Deacon wrote: > > On Mon, Aug 20, 2012 at 10:07:54AM +0100, Will Deacon wrote: > > > On Fri, Aug 17, 2012 at 08:06:07AM +0100, Arnd Bergmann wrote: > > > > Sorry for the dumb question, but why do you even need PTRACE_GET_THREAD_AREA > > > > for 64 bit tasks? I thought the thread pointer is a GPR, or is this just > > > > for compat tasks? > > > > > > The TLS is stored in a co-processor register which is read-only for > > > userspace. > > > > I should elaborate: the register is RW for AArch64 tasks, RO for aarch32 > > tasks (although that doesn't affect the need for the ptrace request). > > So can't you just /add/ that register to the GPR regset? We *could*, but it doesn't feel right to me. The TLS register: - Can only be manipulated by msr/mrs instructions - Is not part of the PCS - Is not accessed explicitly by user applications - Can not be written via ptrace so I think it sticks out like a sore thumb if we bundle it up with the GPRs. Will -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
